guy-incognito

This is a common misconception: According to the measurements made by tftcentral, the XB270HU is actually faster than the PG278Q, because it has a faster signal processor / scaler. So the pixels are a bit slower on the XB270HU, but the overall input lag is still lower. See here. (Or more specifically, this diagram.)

I will switch to 4K when its two main drawbacks (imho) are sorted out: 1. The 60 Hz limit: I don't want to go back from 120/144 Hz to 60... no way.. 2. Scaling in Windows. I hope Windows 10 will fix this for good (or the developers of applications that don't support scaling properly, get it sorted out...) Until then, 1440p is where I want to be (Bonus point 3.: when I can afford powerful enough graphics card(s) )

1440p on 27" is a very good compromise between sharpness and performance requirements. (And currently the highest possible resolution for 144 Hz.) But don't be fooled: pixels are still very visible and anti-aliasing is still very necessary. The resolution is 109 ppi, which is only about 20% more than a common 1080p 24" monitor has (92 ppi). A 28" 4K monitor has 157 ppi, which is a whole new level of sharpness. In my opinion, THIS is the point where resolution is high enough. You almost don't need anti-aliasing anymore, and pixels are barely noticable if you sit like half a meter away from the screen.

I've said it before and I'll say it again: Go for IPS, you won't regret it! There are basically two objective reasons to get the ROG Swift and not the Acer: You have an Nvidia 3D Vision kit and play a lot of stereoscopic 3D games. (The Acer does not support that.) You want a super-slim matte bezel and a more "elegant" design. (The Acer has a glossy bezel and a blue LED in the bottom right, which some say is ugly.) In all other aspects, the Acer XB270HU is better than the ROG Swift, or at least equal. And yes, I know that the XB270HU has a slightly slower pixel response time, because it's an IPS panel. But thanks to its faster signal processing, this is a non-issue, as documented by tft-central. (See the section "Lag" / "Lag classification")

I'd say the 970 is good enough for 1440p, if 60 fps is enough for you. Maybe in some games you'll have to reduce a few settings, but you won't need that much anti-aliasing on a 1440p panel anyway, and in my opinion the higher resolution is absolutely worth it. (I'm running most current games on ultra with a single 980 in 1440p resolution.) I'd suggest going for a 1440p IPS/PLS panel.

In theory, yes. But few games really work that well. In practice, you have to make compromises like lowering the details and switching off some lighting, shadows and/or post-processing effects. There are lots of games that do not render properly with max. settings.

Acer XB280HK, the only one with G-Sync, which is a great plus if you have an Nvidia card (or cards)

Problem is, there is no absolute answer to the "big question" of 144hz,1440p, IPS vs 60hz,4k,TN... Other people will have other priorities. I'm sure there is someone out there who will value the 4K resolution more than anything else... Another thing to consider is, when going for a 4K monitor, you will have to use scaling in Windows, which many applications don't support properly (results in blurry text). It's a bit better in Windows 8 than in Windows 7, but still not perfect. Hopefully Windows 10 will fix that...

Yes you will notice the higher pixel density. (You still need strong anti-aliasing on a 1440p 27" monitor. Not so much on a 4K 28" one.) No you will not notice lag on the the XB270HU. It is perfectly suited for competetive gaming. (Comparison chart by TFT Central) Exactly "how much" better it is, is very subjective. For me, it's a big difference, especially due to the absence of vertical brightness shift. I have the XB270HU for a few weeks now, and I wouldn't want to go back to a TN panel, no matter the resolution. And the capability to run games at 144 fps is really great, too. But on the other hand, I've never seen gaming on a 4K monitor in person. So maybe that would change my view... I don't know Edit: You say you want IPS and high refresh rates, but also a higher resolution. For me that looks like a 2:1 win for the XB270HU

With a good monitor, and most importantly with good games, it is absolutely worth it in my opinion. But the problem is, there are no more good games coming out that are optimized for 3D Vision. The thing is, if the game is not properly optimized, you won't have a lot of fun. I tried many games and with many, I found myself turning 3D Vision off again pretty quickly. Especially lighting, shadow or smoke/fog effects often render incorrectly, which is a pain for your eyes. But then there are the "3D vision ready" games (List). When everything is rendered at the correct depth and all the effects work, the overall experience can be spectacular! And this list is not complete. Notable games missing, that have perfect 3D Vision support are Tomb Raider (2013), Crysis 3 and Metro Last Light. Especially the Metro series... it's immersive like nothing you've ever seen... Will keep you on the edge of your seat. So... is it still worth it? If you already have a compatible monitor (with Lightboost!) and a strong enough graphics card (minimum 770 or 680 for 1080p), I'd say go for it. Especially if you have not yet played those games I mentioned. The extra investment is not that much, and as I said, for some games the experience is simply fantastic. But if you'd have to make a bigger investment to get into 3D Vision, then it will probably be better to just wait for the next generation, i.e. VR. (Since almost no new games coming out 2015 will support 3D Vision anyway...)

Exactly. No need for a 3D Vision monitor anymore But right now, support for Nvidia 3D Vision is actually decreasing! There have been some really great games in the last couple years, like I mentioned (Tomb Raider, Crysis 3, Metro...) But what game of 2015 has proper 3D Vision support? (I mean without having to make compromises by turning certain features off that would otherwise cause graphical glitches in stereo 3D...)

I've got the XB270HU now and I'm extremely happy with it. I would never have thought how much of a difference the absence of vertical brightness shift makes! Wouldn't want to go back to a TN panel now. Overall the image looks stunning with great colors and contrast, although that is subjective, of course. The thing with 3D Vision support is, it was great while it lasted, but there are no new games coming out that properly support it. So the loss is minimal. This is the main factor that initially helped me decide in favor of the XB270HU, and I'm more than satisfied with the outcome.

According to users of the german forum HardwareLuxx, there are indeed "issues" with the XB270HU. They made a poll, but only 13 users have participated yet. 8 say they have either no issues at all, or small issues that are not distracting, like minor backlight bleed (including myself). 5 say they have issues with backlight bleed and/or dead pixels, being very noticable and distracting. Of course, all this is highly subjective... I think it should not stop anyone from buying the XB270HU, because it's still a great piece of hardware overall. If it's really too bad (i.e. if you have dead pixels, or very strong backlight bleed), just return it.

You still get vertical brightness shift on the Swift. Not even the best TN panel can get around that... For me personally, that's a no-go. Well, it is at least since I've seen the Predator in person.

But that would be the XB270HA (1080p TN), not the HU (1440p IPS). To answer op: I'd also go for the XB270HU. Mainly because IPS.